CVE-2026-54350

Budibase is an open-source low-code platform. Prior to 3.39.12, an unauthenticated visitor of any published Budibase app reads every document of the backing MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST-with-JSON-body collection and, where the builder has published a PUBLIC write query, modifies every document of that collection with one HTTP request. enrichContext at packages/server/src/sdk/workspace/queries/queries.ts:121-138 substitutes parameter values into the raw JSON body of a query, then JSON.parses the result. The validator validateQueryInputs at packages/server/src/api/controllers/query/index.ts:61-71 rejects only Handlebars markers ({{, }}) in user input and does not escape JSON metacharacters (", , }). A parameter value containing a closing quote and additional keys lifts attacker-controlled fields into the parsed filter object. For Mongo find, the parsed filter passes directly to collection.find() (packages/server/src/integrations/mongodb.ts:506-510). Duplicate-key JSON parsing overrides the builder's {name: "..."} with {name: {$exists: true}} and returns every document. The same primitive against an updateMany query (mongodb.ts:577-585) widens the filter scope to the full collection while the builder-controlled $set body runs against every matched document. The authorized middleware at packages/server/src/middleware/authorized.ts:141-148 short-circuits when the query's role is PUBLIC. CSRF is not enforced on this path. POST /api/v2/queries/:queryId (packages/server/src/api/routes/query.ts:63) accepts the call with no session, only an x-budibase-app-id header that is public from the published-app URL. This vulnerability is fixed in 3.39.12.

Budibase is an open-source low-code platform. Prior to 3.39.12, an unauthenticated visitor of any published Budibase app reads every document of the backing MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST-with-JSON-body collection and, where the builder has published a PUBLIC write query, modifies every document of that collection with one HTTP request. enrichContext at packages/server/src/sdk/workspace/queries/queries.ts:121-138 substitutes parameter values into the raw JSON body of a query, then JSON.parses the result. The validator validateQueryInputs at packages/server/src/api/controllers/query/index.ts:61-71 rejects only Handlebars markers ({{, }}) in user input and does not escape JSON metacharacters (", , }). A parameter value containing a closing quote and additional keys lifts attacker-controlled fields into the parsed filter object. For Mongo find, the parsed filter passes directly to collection.find() (packages/server/src/integrations/mongodb.ts:506-510). Duplicate-key JSON parsing overrides the builder's {name: "..."} with {name: {$exists: true}} and returns every document. The same primitive against an updateMany query (mongodb.ts:577-585) widens the filter scope to the full collection while the builder-controlled $set body runs against every matched document. The authorized middleware at packages/server/src/middleware/authorized.ts:141-148 short-circuits when the query's role is PUBLIC. CSRF is not enforced on this path. POST /api/v2/queries/:queryId (packages/server/src/api/routes/query.ts:63) accepts the call with no session, only an x-budibase-app-id header that is public from the published-app URL. This vulnerability is fixed in 3.39.12.

Summary

enrichContext at packages/server/src/sdk/workspace/queries/queries.ts:121-138 substitutes parameter values into the raw JSON body of a query, then JSON.parses the result. The validator validateQueryInputs at packages/server/src/api/controllers/query/index.ts:61-71 rejects only Handlebars markers ({{, }}) in user input and does not escape JSON metacharacters (", \, }). A parameter value containing a closing quote and additional keys lifts attacker-controlled fields into the parsed filter object.

For Mongo find, the parsed filter passes directly to collection.find() (packages/server/src/integrations/mongodb.ts:506-510). Duplicate-key JSON parsing overrides the builder's {name: "..."} with {name: {$exists: true}} and returns every document. The same primitive against an updateMany query (mongodb.ts:577-585) widens the filter scope to the full collection while the builder-controlled $set body runs against every matched document.

The authorized middleware at packages/server/src/middleware/authorized.ts:141-148 short-circuits when the query's role is PUBLIC. CSRF is not enforced on this path. POST /api/v2/queries/:queryId (packages/server/src/api/routes/query.ts:63) accepts the call with no session, only an x-budibase-app-id header that is public from the published-app URL.

Result: an unauthenticated visitor of any published Budibase app reads every document of the backing MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST-with-JSON-body collection and, where the builder has published a PUBLIC write query, modifies every document of that collection with one HTTP request.

Affected

Budibase/budibase server, @budibase/server package, <= 3.39.0 (HEAD feab995, released 2026-05-20).

Reachable on any deployment where a workspace builder has set the role of a non-SQL query (MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST with bodyType=json) to PUBLIC and published the app. This is the canonical low-code public-form use case.

SQL datasources (Postgres, MySQL, MSSQL, Oracle, MariaDB) route through interpolateSQL and are not affected.

Root cause

packages/server/src/sdk/workspace/queries/queries.ts:121-138: processStringSync(fields[key], parameters, {noEscaping: true, noHelpers: true}) writes the raw parameter value into the JSON-body string with no JSON-string escape; the followup JSON.parse(enrichedQuery.json || enrichedQuery.customData || enrichedQuery.requestBody) lifts the substituted text into the integration filter object.

packages/server/src/api/controllers/query/index.ts:61-71: validateQueryInputs only rejects values where findHBSBlocks(value).length !== 0 (Handlebars markers) and ignores JSON metacharacters.

packages/server/src/integrations/mongodb.ts:506-510: collection.find(json) receives the user-controlled filter object directly with no key prefix or operator allow-list.

packages/server/src/integrations/mongodb.ts:577-585: collection.updateMany(json.filter, json.update, json.options) accepts the templated filter without verifying that the substituted filter still matches the builder's intent.

packages/server/src/middleware/authorized.ts:141-148: if (resourceRoles.includes(roles.BUILTIN_ROLE_IDS.PUBLIC)) return next() skips both authentication and CSRF.

packages/server/src/integrations/queries/sql.ts:29-122: interpolateSQL rewrites every {{ binding }} to a positional bind placeholder ($N or ?). The SQL leg is bind-parameterised; the JSON leg is not.

Reproduction

budibase/budibase:latest (v3.39.0) Docker single-container, default config. Builder logs in once, creates a MongoDB datasource, creates a query GetUserByName with body { "name": "{{ name }}" }, sets the query role to PUBLIC, and publishes the app.

1. Anonymous client sends the inject payload to the read query.

POST /api/v2/queries/<read-queryId> HTTP/1.1
Host: <budibase-host>
x-budibase-app-id:…

Budibase is an open-source low-code platform. Prior to 3.39.12, an unauthenticated visitor of any published Budibase app reads every document of the backing MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST-with-JSON-body collection and, where the builder has published a PUBLIC write query, modifies every document of that collection with one HTTP request. enrichContext at packages/server/src/sdk/workspace/queries/queries.ts:121-138 substitutes parameter values into the raw JSON body of a query, then JSON.parses the result. The validator validateQueryInputs at packages/server/src/api/controllers/query/index.ts:61-71 rejects only Handlebars markers ({{, }}) in user input and does not escape JSON metacharacters (", , }). A parameter value containing a closing quote and additional keys lifts attacker-controlled fields into the parsed filter object. For Mongo find, the parsed filter passes directly to collection.find() (packages/server/src/integrations/mongodb.ts:506-510). Duplicate-key JSON parsing overrides the builder's {name: "..."} with {name: {$exists: true}} and returns every document. The same primitive against an updateMany query (mongodb.ts:577-585) widens the filter scope to the full collection while the builder-controlled $set body runs against every matched document. The authorized middleware at packages/server/src/middleware/authorized.ts:141-148 short-circuits when the query's role is PUBLIC. CSRF is not enforced on this path. POST /api/v2/queries/:queryId (packages/server/src/api/routes/query.ts:63) accepts the call with no session, only an x-budibase-app-id header that is public from the published-app URL. This vulnerability is fixed in 3.39.12.

Budibase is an open-source low-code platform. Prior to 3.39.12, an unauthenticated visitor of any published Budibase app reads every document of the backing MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST-with-JSON-body collection and, where the builder has published a PUBLIC write query, modifies every document of that collection with one HTTP request. enrichContext at packages/server/src/sdk/workspace/queries/queries.ts:121-138 substitutes parameter values into the raw JSON body of a query, then JSON.parses the result. The validator validateQueryInputs at packages/server/src/api/controllers/query/index.ts:61-71 rejects only Handlebars markers ({{, }}) in user input and does not escape JSON metacharacters (", , }). A parameter value containing a closing quote and additional keys lifts attacker-controlled fields into the parsed filter object. For Mongo find, the parsed filter passes directly to collection.find() (packages/server/src/integrations/mongodb.ts:506-510). Duplicate-key JSON parsing overrides the builder's {name: "..."} with {name: {$exists: true}} and returns every document. The same primitive against an updateMany query (mongodb.ts:577-585) widens the filter scope to the full collection while the builder-controlled $set body runs against every matched document. The authorized middleware at packages/server/src/middleware/authorized.ts:141-148 short-circuits when the query's role is PUBLIC. CSRF is not enforced on this path. POST /api/v2/queries/:queryId (packages/server/src/api/routes/query.ts:63) accepts the call with no session, only an x-budibase-app-id header that is public from the published-app URL. This vulnerability is fixed in 3.39.12.

Summary

enrichContext at packages/server/src/sdk/workspace/queries/queries.ts:121-138 substitutes parameter values into the raw JSON body of a query, then JSON.parses the result. The validator validateQueryInputs at packages/server/src/api/controllers/query/index.ts:61-71 rejects only Handlebars markers ({{, }}) in user input and does not escape JSON metacharacters (", \, }). A parameter value containing a closing quote and additional keys lifts attacker-controlled fields into the parsed filter object.

For Mongo find, the parsed filter passes directly to collection.find() (packages/server/src/integrations/mongodb.ts:506-510). Duplicate-key JSON parsing overrides the builder's {name: "..."} with {name: {$exists: true}} and returns every document. The same primitive against an updateMany query (mongodb.ts:577-585) widens the filter scope to the full collection while the builder-controlled $set body runs against every matched document.

The authorized middleware at packages/server/src/middleware/authorized.ts:141-148 short-circuits when the query's role is PUBLIC. CSRF is not enforced on this path. POST /api/v2/queries/:queryId (packages/server/src/api/routes/query.ts:63) accepts the call with no session, only an x-budibase-app-id header that is public from the published-app URL.

Result: an unauthenticated visitor of any published Budibase app reads every document of the backing MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST-with-JSON-body collection and, where the builder has published a PUBLIC write query, modifies every document of that collection with one HTTP request.

Affected

Budibase/budibase server, @budibase/server package, <= 3.39.0 (HEAD feab995, released 2026-05-20).

Reachable on any deployment where a workspace builder has set the role of a non-SQL query (MongoDB, CouchDB, Elasticsearch, DynamoDB-PartiQL, or REST with bodyType=json) to PUBLIC and published the app. This is the canonical low-code public-form use case.

SQL datasources (Postgres, MySQL, MSSQL, Oracle, MariaDB) route through interpolateSQL and are not affected.

Root cause

packages/server/src/sdk/workspace/queries/queries.ts:121-138: processStringSync(fields[key], parameters, {noEscaping: true, noHelpers: true}) writes the raw parameter value into the JSON-body string with no JSON-string escape; the followup JSON.parse(enrichedQuery.json || enrichedQuery.customData || enrichedQuery.requestBody) lifts the substituted text into the integration filter object.

packages/server/src/api/controllers/query/index.ts:61-71: validateQueryInputs only rejects values where findHBSBlocks(value).length !== 0 (Handlebars markers) and ignores JSON metacharacters.

packages/server/src/integrations/mongodb.ts:506-510: collection.find(json) receives the user-controlled filter object directly with no key prefix or operator allow-list.

packages/server/src/integrations/mongodb.ts:577-585: collection.updateMany(json.filter, json.update, json.options) accepts the templated filter without verifying that the substituted filter still matches the builder's intent.

packages/server/src/middleware/authorized.ts:141-148: if (resourceRoles.includes(roles.BUILTIN_ROLE_IDS.PUBLIC)) return next() skips both authentication and CSRF.

packages/server/src/integrations/queries/sql.ts:29-122: interpolateSQL rewrites every {{ binding }} to a positional bind placeholder ($N or ?). The SQL leg is bind-parameterised; the JSON leg is not.

Reproduction

budibase/budibase:latest (v3.39.0) Docker single-container, default config. Builder logs in once, creates a MongoDB datasource, creates a query GetUserByName with body { "name": "{{ name }}" }, sets the query role to PUBLIC, and publishes the app.

1. Anonymous client sends the inject payload to the read query.

POST /api/v2/queries/<read-queryId> HTTP/1.1
Host: <budibase-host>
x-budibase-app-id:…